IMX6ULL: USB disconnection issue

[velayutha_perum]

Hi,

      I am using custom IMX6ULL board. I am getting below prints whenever switching off 3G modem (Quectel UC15) which  is interfaced to processor via USB.

ci_hdrc ci_hdrc.1: remove, state 1
usb usb1: USB disconnect, device number 1
usb 1-1: USB disconnect, device number 2
option1 ttyUSB0: GSM modem (1-port) converter now disconnected from ttyUSB0
option 1-1:1.0: device disconnected
option1 ttyUSB1: GSM modem (1-port) converter now disconnected from ttyUSB1
option 1-1:1.1: device disconnected

option1 ttyUSB2: GSM modem (1-port) converter now disconnected from ttyUSB2
option 1-1:1.2: device disconnected
option1 ttyUSB3: usb_wwan_indat_callback: resubmit read urb failed. (-19)
option1 ttyUSB3: usb_wwan_indat_callback: resubmit read urb failed. (-19)
option1 ttyUSB3: usb_wwan_indat_callback: resubmit read urb failed. (-19)
option1 ttyUSB3: usb_wwan_indat_callback: resubmit read urb failed. (-19)
iwave: netlink_link_state: Link ppp0 Down
option1 ttyUSB3: GSM modem (1-port) converter now disconnected from ttyUSB3
option 1-1:1.3: device disconnected

option1 ttyUSB2: usb_wwan_indat_callback: resubmit read urb failed. (-19)
option1 ttyUSB2: usb_wwan_indat_callback: resubmit read urb failed. (-19)
option1 ttyUSB2: usb_wwan_indat_callback: resubmit read urb failed. (-19)
option1 ttyUSB2: usb_wwan_indat_callback: resubmit read urb failed. (-19)
option1 ttyUSB4: GSM modem (1-port) converter now disconnected from ttyUSB4
option 1-1:1.4: device disconnected
ci_hdrc ci_hdrc.1: USB bus 1 deregistered

In the above print ttyUSB2 is AT port and ttyUSB3 is used for network connection. 

The 3G Modem vendor stated that this usb_wwan_indat_callback: resubmit read urb failed was given by Modem manager which is related to Linux kernel. It was resolved by adding some patch for kernel.

Can you help us finding the patch ? Also can you let us know what is the reason for this issue and what could be done to resolve this.

Many thanks in advance!!!

Regards,

Peru

[weidong_sun]

Hi velayutha,

The problem you are experiencing is not due to the lack of a patch.

The migration of 3G / 4G requires the following steps:

1. Adding VID/PID to drivers/usb/serial/option.c 

2. Loading USB for GSM and CDMA driver in linux kernel

3. Adding usb networking support

4. Power Down Pins of 3G/4G module

We should notice the PWDN pin, most of 3G/4G module needs to pull down the pin to LOW and keep longer time ,then pull it up to HIGH, otherwise, no ttyUSBx devices are created. So about the time, you can try 100ms , 200ms, or Higher one.

Hope above information can help you.

Have a nice day!

BR,

Weidong